Project Summary Our study focuses on the prevalence and identification of kidney disease among participants of the WTC Health Program and we are planning to assess kidney disease in a multi-factorial manner. The first aim of our study is to correlate kidney dysfunction with 9/11 exposure, and we predict that exposure to 9/11 is an independent risk factor in kidney disease among the WTC Health Program participants. Secondly, we propose that a well-established WTC-related condition, obstructive sleep apnea (OSA), is independently associated with kidney disease. In addition, we believe there is a temporal causative relationship between evidence of kidney disease and the severity of OSA. Finally, our last aim is to further identify and explore potential mechanisms and phenotypes of kidney disease in participants of the WTC Health Programs. Successful completion of the proposed research would address a critical knowledge gap regarding the risk of kidney damage among this group of patients, and would inform future mechanistic studies with the potential to impact prevention.